Carrier Tested Different Plans, Including an Unlimited Offer for $50 a Month

OVERLAND PARK, Kan.—New Sprint Corp. chief Marcelo Claure has been following John Legere on Twitter since February. Now, he is gearing up to try to get ahead of his T-Mobile US Inc. counterpart in the market.

Mr. Claure is preparing to roll out new price plans next week that could offer much cheaper prices, much bigger allotments of wireless...